1. Field of the Invention
The present invention relates to portable devices and, more particularly, to an apparatus and method for conserving a charge of a battery in a portable device.
2. Description of the Related Art
There has been a recent proliferation of portable devices capable of performing multiple functions such as a communication function, a personal organizer function, a camera function, a game function, and/or a music player function. As these devices have been developed to perform functions at higher speeds, the power consumption of these devices has considerably increased. Accordingly, it is becoming more important to manage the power consumption of these devices effectively.
To operate a portable device, a battery which supplies power to the portable device must have a charge of at least a minimum voltage, referred to as a cutoff voltage. When the battery charge decreases below this cutoff voltage, the portable device will shut off.
For example, a conventional Global System for Mobile communications (GSM) mobile terminal utilizes a lithium-ion battery which has a capacity of 4.2 V. The conventional GSM mobile terminal has a cutoff voltage of 3.4 V, and will thus shut off when the charge of the battery drops below 3.4 V.
Due to chemical properties of a battery, if an output current of the battery severely fluctuates, this causes the battery charge to drain quickly. In contrast, when the output current of the battery is relatively constant, the battery charge does not drain as quickly.
Further, the larger the current the battery outputs, the more the battery charge drains.
FIG. 1 shows a block diagram of a conventional portable device.
The conventional portable device shown in FIG. 1 includes a battery 12 which supplies power to electronic circuitry 16 of the device, which includes a Power Amplifier Module (PAM) 14 that directs connects to the battery 12.
The battery 12 supplies power to the electronic circuitry 16 through the PAM 14. When the charge of the battery 12 drops below a cutoff voltage, the portable device shuts off.
The electronic circuitry 16 is powered by an electric current provided by the battery 12. During some modes of operation of the portable device, the current requirement of the electronic circuitry 16 fluctuates. For example, FIG. 2 shows a graph of exemplary current requirements of the electronic circuitry 16 of a portable device while it is in a call communication mode. As shown in FIG. 2, the current requirement fluctuates between a peak current of 2.1 A, and a low current of 20 mA.
Since the output current of the battery 12 severely fluctuates, this causes the battery charge to drain quickly, as mentioned above. When the charge of the battery 12 drops below the cutoff voltage, the portable device shuts off.